The present invention is in the field of blowout preventor assemblies for preventing the upward flow of excessive gas (or any other) pressure from a subterranean source during the drilling or production of an oil or gas well. Also, the present invention features a device which is in the field of oil well fishing or article retrieval apparatus, in an alternative embodiment thereof.
In many instances, oil and/or gas wells develop extreme pressure, or for some other reason, control valves and other structures at the surface of the oil rig are destroyed or damaged resulting in uncontrollable loss of well fluid, and in some instances, the flowing fluids are ignited and the well burns out of control. Many proposals have been made heretofore for capping or shutting off flow from such blownout or burning wells but none have proven completely successful. It has been proposed to clamp a multipart housing around a well casing above the ground surface and by means of devices within the housing to collapse and flatten the casing at some point therein to shut off flow from the well and then to perforate the casing below the closure and withdraw well fluids from the housing. Such a proposal is shown in U.S. Pat. No. 1,949,672. Another proposal has been to bolt or otherwise secure a multipart housing around a well casing and shearing knives within the housing are operated by hydraulic means or otherwise to shear through the casing within the housing, the shearing knives themselves then serving as a gate valve to close the well. Such a proposal is shown in U.S. Pat. No. 1,875,673. Such proposals, however, have not been successful since the shearing knives do not make a smooth cut and a satisfactory seal between the knives and casing has not been achieved. Other proposals for closing blownout or burning wells involve the provision as a permanent part of the well casing, certain valve-like devices for shutting off flow.